1. Field of the Invention
The present invention is related to methods and apparatus for controlling urinary incontinence.
2. Background of the Invention
Urinary incontinence is an extremely widespread problem within the United States and throughout the world. Urinary incontinence affects people of all ages, but is especially common among older people. It is estimated that close to one million Americans are candidates for surgical correction of urinary incontinence through measures such as the implantation of an artificial urinary sphincter. Urinary incontinence has a multiplicity of causes including accidents, disease, or embryonic defect.
Urinary incontinence is a potentially serious condition, both physiologically and psychologically. In older children and in adults the inability to control one's bladder can have severe psychological impacts. In a patient in an otherwise weakened state, such as an aged person, urinary incontinence may affect the person's very will to live. While in such a condition, dealing with urinary incontinence, including the use of diapers and the like, can be devastating to a person's ego and self-image. As a result, it is necessary that methods and apparatus be developed which can effectively and efficiently control urinary incontinence in order to avoid such adverse impacts.
Urinary incontinence is also serious and detrimental to a patient's physical well-being This condition may require surgery, with its associated dangers and traumas, or it may require the use of catheters in treatment. Both alternatives have potential adverse physical effects including tissue damage and infection, as will be discussed below.
The urinary tract comprises a series of components. Initially, blood flows into the kidneys where it is processed through individual kidney nephrons Blood then flows out of the kidney and returns to the general vascular system. Excess water, minerals, and metabolic end products are removed from the blood as it flows through the kidneys. This material is collected and eventually becomes urine.
After urine is formed in the kidney, it exits the kidney through the ureters. Ureters comprise tubes which connect the kidneys with the bladder A pair of ureters, one from each kidney, direct urine flow into the bladder. Thus, urine will continue from the kidneys, through the ureters, and into the bladder. 22 The bladder is in essence a storage vessel for urine. Urine will collect in the bladder until the bladder is relatively distended. Generally, an adult bladder will hold approximately one pint of fluid. Once the bladder is full, it is necessary to void the bladder. When this occurs the interconnection between the bladder and the urethra is opened by the mechanism described below, and urine flows into the urethra. The urethra in turn carries urine out of the body.
Urinary bladder continence is generally attributed to the tonic contraction of the smooth muscle arranged in the bladder neck. This muscle structure forms the so-called internal sphincter. While not a true sphincter, the funnel-like passage formed by this "trigone region" of the bladder and the urethra, effectively prevents urine flow while in the continent state.
Although knowledge of the physiology of the urinary bladder and urethra is incomplete, continence is generally attributed to the internal sphincter. While not a true sphincter the apposition of the tissue of the trigone and proximal urethra form a purse-like closure of the bladder neck. The base of a normally functioning bladder appears to be flat except during micturition (urination). At that time relaxation of several abdominal muscles, principally the pubo-coccygeus, occurs, the bladder falls and the detrusor contracts forming a funnel-like opening at the bladder neck. Vesical pressure increases, due to abdominal contraction as well as the tonus of the bladder wall, and the urine flows into the urethra. Expansion of the urethra produces a reflex action which causes a further increase in the vesicle pressure. This feedback process continues until the bladder is emptied.
In most children older than four years, it is possible for the higher brain centers to prevent actual urination by holding the external sphincter closed after the urge to void is felt. In the micturition sequence, the cortical centers release the neutral excitation and the urethra relaxes to permit urine passage. If the external sphincter is not relaxed, the contracting detrusor muscle can generate pressures high enough to produce tissue damage.
Urinary incontinence occurs when an individual is unable to control the muscle relaxation sequence described above. In incontinent individuals, urine may flow into the urethra regardless of attempts by the individual to control that flow.
In order to control urinary incontinence, many types of devices have been developed. One class of devices essentially constitutes a cuff or similar structure which is surgically implanted around the exterior wall of the urethra. When it is desired to prevent urine flow, the cuff is hydraulically or mechanically closed so that it is positioned tightly around the urethra. Using this type of device the urethra is physically closed by the pressure of the cuff. When it is desired to void the bladder, the external urethra cuff is retracted or relaxed so that the urethra may again open. Once this occurs, urine is free to pass through the urethra and exit the body.
The method of operation of these cuff devices is in direct contrast to the natural method of maintaining continence. The natural method does not involve compressive forces around the exterior of the urethra, but rather the lifting or dropping of the position of the bladder neck. As a result of the unnatural method of operation of these devices, the cuff devices tend to cause severe tissue damage (tissue necrosis) as well as thickening and scaring of the urethra wall. This tissue damage may make it increasingly difficult for the cuff device to effectively close the urethra and for the urethra to reopen when the pressure is released. Because of these problems, cuff devices are only usable for a short period of time before serious difficulties with their use develop. In addition, these devices may become encapsulated during the period of implantation and may fail to properly operate after a relatively short period of time.
It must also be remembered that a contracting detrusor muscle can possibly generate pressures high enough to cause tissue damage. In a bladder capable of reflective contraction, the cuff type artificial sphincter must be used with extreme care since to maintain the continent state in the face of increased vesicle pressure requires a very large compressive force around the urethra. The resulting forces can produce severe tissue damage to the patient. Indeed, with reflexive bladders, it is a common practice to resect the nerves to the external sphincter in order to prevent vesicle tissue damage.
Methods and devices have also been used to physically contract the urethra without using a full cuff. For example, one method involves implanting a cylinder containing a magnet on one side of the urethra external to the urethra. The urethra is then compressed by placing a magnet outside of the body on the distal side of the urethra. As a result, the implanted magnet is forced against the outside wall of the urethra and theoretically contracts or pinches the urethra sufficiently to maintain continence. When it is desired to void the bladder, the external magnet is removed and the forces against the urethra are relaxed, thus allowing urine flow.
This type of device suffers the same disadvantages as those discussed with respect to the cuff. In particular, the constant pressure against the urethra wall may cause severe tissue damage. In addition, the implanted magnet may become encapsulated within the body. Further, it may be difficult to provide magnets powerful enough to effectively compress the urethra over long periods of time in the manner disclosed by this device.
Another approach to controlling incontinence has been to insert an inflatable bulb through the urethra into the bladder. A catheter is permanently attached to the bulb and exits the body through the urethra. When a continent state is desired, the bulb is inflated by means in communication with the external end of the catheter. When it is desired to void the bladder, the bulb is simply deflated such that it no longer blocks the bladder outlet.
There are several problems encountered with the use of this type of device. The most serious problem is that the catheter which exits the body is a direct passageway to the bladder for infection. As a result, it is necessary to continually use antibiotics when this type of device is in place. The antibiotics, in turn, may have serious damaging side effects. As a result, this type of device can only be used for a very short period of time and cannot be used as a long-term treatment of incontinence.
Other types of mechanical devices have been inserted through the urethra into the base of the bladder. These devices are generally mechanically or electrically actuated valves of various descriptions. These valves, however, are quickly encrusted by components of the body fluids which they contact. As a result, they generally fail in a short period of time. In addition, having such valves permanently implanted within the urethra or bladder may cause tissue damage of the type described above.
As a result of the problems discussed above, it is found that many of the existing devices used to control urinary incontinence are not generally usable; or if they are usable, they are usable for only a short period of time. It has been found in the art that a high percentage of devices implanted are prematurely removed because of the problems discussed above. As a result, patients are subjected to the trauma of repeated surgeries without receiving a satisfactory cure for incontinence. It can, therefore, be appreciated that satisfactory methods and apparatus are not presently available for controlling urinary incontinence.
It is apparent that what is needed in the art are methods and apparatus for maintaining urinary continence in normally incontinent individuals. In particular, it would be a significant advancement in the art to provide an apparatus for maintaining urinary continence which was simple, reliable, and not prone to mechanical or electrical failure when implanted within the body. It would also be an advancement in the art if such an apparatus could be implanted and removed nonsurgically. It would be a further advancement in the art to provide an apparatus for maintaining continence which did not significantly damage the tissues of the bladder, urethra, or surrounding areas. It would also be an advancement in the art to provide methods and apparatus for maintaining urinary continence which could do so over extended periods of time. Such methods and apparatus are disclosed and claimed herein.